Magnetic separator and concentrator



Aprii '27;"- 1937. R. H. STEARNS 2,078,513

MAGNETIC SEPARATOR AND CONCENTRATOR Filed Dec. 11, 193; 4 Sheets-Sheet 1 2/ /6 Z I 6/44/1615 63 55; Z8 6-5192 5a x INVENTOR ATTORNEYS A' ril 27, 1937.

R. H. STEARNS MAGNETIC SEPARATOR AND CONCENTRATOR Filed Dec. 11, 1933 4-Sheets-Sheet 4 INVENTOR W ATTORNEYfi Patented Apr. 2' 7, v 1937 UNITED STATES "PA-TENT oFl-lcs amsls-f moua'nc summit. in

. commune-ma *1: Claims. (01. 209-219) This invention relates to improvements in mag- ,netic separators and concentrators.

Broadly stated, it is theprimary obiect of the present invention to-provide a novel and improved form of magnetic separating device organized to ciency of the apparatus isimproved by reason of a closed circuit arrangement having. a field core through which some of the magnetic mate- ,rial. may be discharged, the frame-like form of e the field core and the means for properly adjust;-

ing. it, andthe means for controlling the flow of material with respect to such core. constituting some ofthe more important features-of the present invention.

Another object cit the invention is to provide .,novel means for handling extremely fine .ma .terials, either-wet or dry,.-through the use of a secondary magnet or field core by which a sub; ,stantially closed magnetic path is provided in 7 order to increase the intensity of the flux at the point of separation. g

. 1; It is a further object of the invention-to provide an organization inv which magnetic lag or re- '.--luctance is 'overcome by an arrangement which enables the material to be handled at any de- -10 sired speed-while preserving it in substantially a this arrangement enablesthe treatment of --st ate of rest with'reference to successive parts 'of the apparatus while it isbeing acted upon 'magnetically. This is very importantbecause the time interval orma neu treatment permittedby materials of high magnetic reluctance.

Further objects include the 'provisionofaz means, and the provision of an organimtion in which means is provided for varying the magnetic force acting upon the material of successivestages so that, desired, web

55 may be made to increase in each of a .of

.singleunit of a modified embodiment Specifically, however-r mypurposes in clude the provisions of means wherein the ei.'ii-.v

"inclusive, a

in a series successive stages from a minimum to a maximum value. I In the drawings: Figure 1 is a vertical transverse section through the apparatus embodying the invention. 5 Figure 2 is a fragmentary front elevation of the device shown in Fig. 1. f Figure 3 is a fragmentary side elevation of the device shown in Fig. 1.

Figure 4 is ,a detail in horizontal section Y p through the device shown in Fig. 1.

Figure 5 is a view partially in side elevation .and partially in transverse section through a of t vention. 15

Figure 6 is a fragmentary detail in perspective showing the magnet, adjustable polepiece, fiel core, and roll, of, the device shown in Fig. 6

Figure? is a diagrammatic view similarto g. .1 showing an embodim entfo'fthe invention parso ticularly adapted to handle very fine dry mate- Figure 8 is a'view' partially in side elevation and partially insectiom-showing amodifledembodlf ment of the invention in which the material is, ,flltered in liquid to facilitate the separating operation.

, Like parts are identified by the same reference characters throughout the several views.

In the construction heavystructural steel frame in is preferably. provided for mounting the various .elements .of .theinvention. This frame includes horizontal supports at 8, 9 and II, and a base If. .The motor I! and gear box I 6 through which 35 the movable portions of the apparatus are driven by a, belt 2|, are conveniently mounted on the v 1 j is adjustable ,to'ail'ord a greater or less opening by meansof the hand operated pinion 28 and the teeth It. on the under surface of the plate.

and improved form of'pole piece, t of a novel and improved material:

In leaving hopper II. the material passes over a series of speed checking baiile plates which are duplicated in successive conduits for each i litfl e in the cascade treatment of the material.

These baiiies are designated by reference characters 30'. 3l,,and 32 respectively. As clearly shown in the drawings these bai'iies are organized in a h sort of throat through which the material passes shown in Figs. 1 4.

' with controlled speed to each successive roll. The

final baille 32 discharges the material across a substantially horizontal portion. The composite result only slightly exceeds the angle of rest of the material, whereby the material would collect on the feeder were it not for the fact that the roll turning in proximity thereto is constantly removing some of the material from the edge of the plate at a rate corresponding to the peripheral rate of movement of the roll. But with continuous regulated feeding of material from the hopper and a continuous movement of the roll or rolls turning in proximity to the lower edge of the last bathe in each series, the material is prevented from coming to rest at its angle or repose, and therefore continuous feeding in a thin layer or filrn becomes possible, whereas attempts heretofore made to feed material vertically to the top of a revolving roller have been unsuccessful in preventing intermittent feeding of relatively thick batches with intervening spaces in which the surface of the roller is substantially bare, The efliciency of amagnetic separator or" this type is quite largely dependent upon-maintaining a continuous feed of a thin layer of mamrial oi substantially uniform thickness across the line of concentrated magnetic 1613:, and by utilizing means for regulating the feed of the material, in combination with means for utilizing the rotary movement of the roller to constantly distribute material tending to come to rest at an angle of repose, the foregoing requirement for high efiiciency can be met.

The rate of flow from a hopper across an inclined feedway of ordinary type cannot be properly controlled. But by employing a bafile 32, oil

set by the flange at its lower end from the vertical center line of the roll, I provide an angle in which the material would reach substantially a state of repose but for the action of the rotating roll in, withdrawing material from thebottoin at a rate proportioned to the rate of roll rotation. If the bafie is set at approximately the angle of repose for such material, the friction of the retained material may be relied upon to prevent the other material from acquiring momentum and from sliding along the bailie to pile up in the angle between it and the pole piece when the rollor ceases to rotate. This motion arresting iriction may be aided by the use of motion arresting baifies 3i, which also assist in predeterminlng the thiclmess of the layer of flowing material.

t is also an important feature of my invention to provide the electromagnet with pole pieces which are formed to concentrate the magnetic flux along a substantially horizontal line in a vertical plane, which is only slightly below the top of the roller, and in a vertical plane which is crossed by the roller at a point where the pole piece is abruptly receding from said plane below said line of concentrated flux. With this arrangement, the pole piece is in a position to cooperate with the baiiie in checking the flow of material immediately when the power is shut oil and thus allow the material to instantly come to rest at said angle of repose without lodging accumulated supplies against said pole piece.

Just beyond each roll is a dividing gate 35 mounted on a rock shaft 36 having an arm 31 adjustable by means of the bolt 38 and hand nut 38 shown in Fig. 3. Through means hereinafter to be described the magnetic and non-magnetic material is discharged from the roll upon difierent trajectories and a separation is efiected by means of the gate, the magnetic material falling down the left hand side of the gate as viewed in Fig. 1

aovasie through a delivery spout 3%, and the material which has not yet responded to the magnetic separation being discharged to the right of the gate, as viewed in Fig. l, and passing through the next throat to the succeeding roll.

In this manner the material separated from the general mass by roll 25 is discharged through the uppermost of the spouts 39. The material separated by the second roll it is discharged through the second of the spouts 39. The material separated by the third roll M is discharged through the third spout 39, and the material separated by rollsl2 and 13 respectively, isdischarged through the fourth and fifth spouts 39. It will be noted that the feed of the material from one stage of separation to the next is achieved by gravity throughout a series of stages. The only moving parts of the apparatus are the ieeder above described and the successive rolls,

each pole piece is brought to a blunt apex about degrees above the horizontal center line oi the adjacent roll it, ll, d2, or 3, and slightly spaced from the roll. Below the apex the pole piece has a curvilinear contour at 57 so patterned as to represent a trajectory curve deviating somewhat from the maximum trajectory of material delivered from the roll. The form of this face or thepole is such as to concentrate the magnetic flux upon the material at the point where separation should be efiected and to provide beyond that point a rapidly and somewhat uniformly diminishing intensity of flux.

The several rolls 25, to, H 42, and 53, are made of magnetic material and there is a transfer of flux between these rolls and the several pole apices to which they are respectively adjacent. The intensity would be small, however, were it not for the fact that a substantially closed magnetic circuit is provided for rolls #15, M, 52, and

43, without interfering with the discharge of the magnetic material separated from the mass under treatment.

For this purpose I employ secondary magnets at 6d of magnetic material, each or which is in the form of a hollow frame through which one of the spouts 39 may extend. The secondary magnets or field members 60 have arcuately surfaced poles Si in extremely close proximity to the adjacent rolls so as to minimize the air gap and assure a high flow of flux through the circuit represented by the magnetic cores 5!, to the poles 53 and 54, the field members 60, and the intervening rolls. Each of the rolls 40, M 42 and 43, is journaled in suitable bearing members 63 mounted-on the field frames 60 as best shown in Figs. 3 and 4.

The entire assembly of field frame 60 and the rolls mounted thereon, is adjustable for the purpose of varying the gap between the magnetic rolls and the poles of the adjacent magnet 50.

It is possible, moreover, for either roll to be adjusted independently of the other. The means for effecting this adjustment will now be described. Each of the field frames is supported on a bar 65 which is horizontally adjustable in a slot 65.

* in one of the frame members 8 and li'lhe bar 85 provides a support upon which the entire frame may be moved bodily or may be moved pivotally, its position being determined by links 81 and 68 connected to its upper and lower portions respectively and pivoted at 89 to nuts 10 (Fig. 4) which are adjustable on screw H by means of shafts l2 and hand wheel 13. Since each of the links 61 and 68 is connected with the other roll through the actuation of the other link by the connections described.

In Figs. 5 and 6 I have illustrated amodified construction employing only a single roll and providing the magnet 50' with a pole member 54' with which the field frame 60' is integral, as clearly shown in Fig. 6.- In order to provide for necessary adjustments in this form of the device, the upper pole 53' of the magnet 50' is provided with a dove-tailed guideway at B5 complementary to the end of the core 16, upon which the pole member 53 is movable as a slide. For adlusting it I may 'employ a screw at it fixed by collar #19 against movement with respect to its mounting plate 80 and turned by means of a hand wheel M to turn in a threaded car 83 on the slidable pole piece E53. Otherwise the device shown in Figs. 5 and 6 involves only such minor changes of design as might be expected in a simplified unit of this type.

Where special separating or concentrating functions are to be performed it may be desirable that the first roll 25 should be operated in a held of less strength than succeeding rolls, the succeeding rolls having their strength successively increased to the maximum. An organization 'for this purpose is shown in Fig. i in which there is a polar extension 85 leading from the pole mernher 553 of the first magnet til. lit will be noted that there is no field or armature frame for this roll and the magnetic efiect is therefore very weak. Any magnetic material drawn from the mass by such an arrangement, and passing down the chute 39,. will have very high magnetic characteristics.

The auxiliary pole extension $35 will take some of the power from pole til so that the flux on roll it will not be as concentrated as would be the case if theextension 85 were not used. Thus, the spout 89 below roll it will also handle mag netlc material of relatively high magmatic charaoteristics. The full strength of the magnets will be exerted on rolls ill, and

The operation will now be summarized.

The material led into the hopper at i? is discharged under the control of plate ill and feeder 26 across a series of bafilcs terminating in the spout 32 from which such material passes to the first roll, 2%. Assuming this roll to be energized weakly, by means of an extension pole t5, the

strongest or the magnetic material in the mass,

under treatment will adhere to the magnetized roll 24 until projected therefrom by the increasing gravity effect (as the magnetic material passes to the under side of the roll) or centrifugal force, or both. In any event, the magnetic material will leave the roll upon a diflerent trajectory from that followed by the material which is not so greatly attracted by the roll. The valve 35 permits a very fine adjustment to be made to separate the trajectory of the non-magnetic material from that of the magnetic material,

ix scram V V 7 H I .3 whereby the less highly attracted material will pass to therlght of the valve, as viewed in Fig. 1,

for further treatment.

The gear box l6 includes the change speed mechanism, not shown in detail, to enable the several rolls to be operatedwith any desired rate of rotation. As above indicated, the material will not feed across the rolls except by the rotation of the rolls and consequently the rate of rotation is a matter of significance controlling the rate of feed as well as the development of centrifugal force.

The material remaining in the mass after th first treatment is passed over the second roll 40 at a rate likewise determinable by the rate of roll tive flux density intensified by the presence of the field members 60, but also by the absence of any detracting element such as the extension 85. Upon each of these rolls in sequence, the material is subjected to magnetic attraction of high intensity and the last of the magnetic material is extracted from the mass before the mass reaches the end of the series and is finally discharged through the spout 87?. Any desired means may be used to restore or convey from the machine the material discharged from the several spouts.

It will be noted that only one handling of the material is necessary, although it is treated magnetically several times in quicl; succession. Where magnetic separators are operated in cascode as in the construction shown in Figs. 1 to i, the polarity of the successive rolls should alternate.

It is particularly to be noted that the present device is such that it will accurately retain any adjustment in which its parts have been fixed and, moreover, that it may be adjusted while the machine is in motion without interfering in any way with any adjustment other than the particular one which is manipulated. The frame is made sufficiently heavy so that it cannot possibly yield under the pull of even the strongest electromagnet. spective field frames or secondary magnets till, instead of being adjusted with reference to the frame, are adjusted with reference to each other. the screw it being fixed against axial movement with respect to the pole, and a nut being linked tightly to the field frame or secondary magnet tit. When any one of the rolls tit- 33 is adjusted with respect to the adjacent magnetic pole, its adjustment will be permanent until a readjustment is made.

Associated with each one of the field frames or secondary magnets ht, is a chute as which is continuous, except for openings for the magnetic poles, for the whole height of the frame til. This chute is rigidly connected with the frame ct to partake of all of its adjusting movements, and it carries the several bailies lit, ti and t2, the valve 35, and the spout 3t, pertaining to each of the The primary magnets Bil and their re- In many respects the devices shown in Figs. 7 and 8 are quite difierent from those previously described, although the characteristic secondary magnet or field frame is found in each of these embodiments of the invention.

The construction shown in Fig. '7 is adapted to handle extremely fine, flour-like material. The hopper I!!! is mounted upon a chute 210, the lower end portion 2' of which isadjustable by a pinion 28 and resting at its upper end upon a support 89. The hopper H is spaced abovethe chute and provided with bottom and front walls of screen cloth at 96 through which the material to be separated is sifted in a thin layer on to the chute. The chute and hopper are caused to vibrate by a conventional vibrator suspended on the chute at 95 and comprising the usual A. C. coil 92 and loose core laminations 93, the vibrations of which shake the'hopper I10 to sift material through the screening and, through vibration, to ensure the-feed of such material down the spout 210.

The rolls 42 and 63 may correspond in all respects to the rolls designated by corresponding reference characters in Fig. l. The secondary magnet or field frame 60 may also be like that shown in Fig. 1, although the polar projections 61 are preferably bored at BID to provide air passages connected with a flexible air hose 6 through which air may be blown to dislodge from the rolls the fine magnetic material which may tend to cling thereto beyond the vertical center line of the rolls.

The primarymagnet 50 is similar to that previously described, but the pole pieces 55!) will be noted to be located below the horizontal center line of the respective adjacent rolls by about 45. The adjustable extensionZ'll of the feed spout 210, and the similarly adjustable extension 2'12 of the spout 320 will be noted to deliver the material to the roll 43 directly in the portion of the magnetic field which is of maximum intensity. The adjustment will preferably be such that the material will come to rest adjacent the roll except as the rotation of the roll is continuously advancing a fine film of the flour-like material from the delivery edge of the adjustable spout extension. Since the material is moving exactlyat the speed of the roll at this point, the magnetic particles will cling tightly to the roll while the non-magnetic particles will tend to drop, sep--, aration being made by means of the valve 35 in each instance.

As in the modifications previously described, the valves 35, discharge spout 39, and all-necessary baflies, are mounted on the conduit or chute 88, which, together with the respective rolls 42 and 43, is made fast to the secondary magnet or field frame 60 to partake of the adjustment thereof in a manner previously described.

In the construction shown in Fig. 8 the invention-is modified to adapt it for use in -a wet operation.. In this device, although two rolls are used, they are used in parallel and the material is treated but once in the particular piece of apparatus shown in Fig. 8.

The material to be treated enters the appara tus simultaneously through the two hoppers 95. Associated with each is a water spray 96 for sluicing the material down the hopper. The rolls 4! are partially submerged in a body of water 91 held in tank 98. In order that the primary magnet may be kept dry it is located above the water level, and in this instance the primary magnet- 50, rather than the secondary magnet 60, is proao'raz sre vided with the pole pieces 6| which partially surround the respective rolls so as to deliver flux thereto without substantial concentration.

The secondary magnet or field frame 60 is submerged in tank and in'this device, it is the secondary magnet 60 that has the sharp apices 55I concentrating magnetic flux on 9. lim

ited portion of the peripheral area of the rolls 4!. The surfaces of the poles 55! of the secondary magnet 60 are preferably covered with a non-magnetic coating at 99 so that there will be little or no tendency for the material separated in passing roll 4| to cling to the field frame.

The hoppers 95 lead to a point below water level immediately adjacent the apices 55! of the secondary magnets, where the magnetic field is most intense. The rotation of the rolls 4! in the direction indicated by the arrows will facilitate the discharge of the wet material across the gap between the rolls 4! and the polar apices 55!. Beyond this gap are the adjustable valves "10 leading through a central funnel-shaped receptacle In! for the magnetic material which is sufficiently attracted by the rolls to be carried past the valves. The non-magnetic material will fall at one side or the other of the secondary magnet 60 and outside of the adjustable gates I00. When a suflicient amount has accumulated in the tank 98 the tank may be drained through pipe "22 under the control of valve I03.

I04 controlled by valve I is provided for the drainage of the chamber III! in which the magnetic material accumulates.

In order to prevent the magnetic material from continuing to adhere to the rolls ll, spray pipes are provided at 16 to wash the ascending side of each roll.' Surplus water accumulating in the tank 98 between the intervals of with.-

A similar pipe suspended on screws [2 adjustable by means of wheels 13 in the nuts 14 connected with the magnet structure.

tion of the rolls at predetermined rates.

I claim:

1. In a magnetic separator, the combination with a magnet provided with spaced poles, of a field frame provided with spaced poles complementary to those of the magnet, rolls mounted on the field frame and positioned between its poles and those of the magnet, a conduit system for delivering material successively over said rolls, said system being carried by the field frame, and means for bodily adjusting said field frame respecting said magnet whereby to vary the flux gap between the respective rolls and the poles of said magnet without afiecting the feed of material respecting said rolls. 1

2. In a magnetic separator, the combination with a magnet having spaced poles, of an apered, a frame upon which the primary magnet is of a plurality of magnets each having upper and lower poles, a field frame with complementary poles associated with each magnet, rolls carried by the respective, field frame adjacent the respective poles thereof, means' for adjusting selectively each end of each field frame with refixed, said frame being provided with a guideway upon which said. secondary magnet is slidably and pivotally movable, .and adjustment means extending between the ends of the respective magnets for the individual adjustment of either end of the secondary-magnet directly with reference to the corresponding end of the primary magnet. l

7. In a magnetic separator, the combination.

with a primary magnet comprising a core, spaced polesprojecting laterally therefrom, and an electrical winding upon said core, of a secondary magnet comprising a frame having a central opening and provided with poles projecting laterally toward the poles of the primary magnet,

spect to the adjacent pole of the magnet, where- 1 by to vary the fiux gapbetween one of the rolls andthe adjacent magnetic pole, material con-'- duits carried by each field frame including'means for guiding material over the successive rolls of that field frame, each of said conduits having a hopper at its upper end and a plurality of discharge spoutsfor relatively magnetic and nonmagnetic material respectively, and means carried by said conduits forefiecting the separation of such material, the hopper of the conduit connected with the lower field frame being of suffi- -magnetic rolls mounted between the respective poles of the primary and secondary magnets and each fixed against displacement with reference to the poles of one of said magnets, means for feeding material across said rolls and including separating equipment, and a discharge chute for some of said material extending through the opening of the secondary magnet, and means for effecting bodily adjustment between the poles of said magnets for the regulation of the flux gap between the respective rolls and the poles upon which said rolls are mounted.

cient dimensions to receive relatively lcss-magnetic material from the hopper discharge spout of the conduit connected withthe upper field frame throughout a normal range of adjusted positions of the respective frames, whereby adjustments may be effected with the device in operation without affecting the functioning of said conduits or separating means.

4. In a magnetic separator; the combination with a core having vertically spaced poles with laterally projecting apices and a winding on said core intermediate of said poles, of magnetic rolls associated with the respective, apices in spaced relation thereto, a secondary magnet in the form of a hollow frame having laterally projecting poles arcuately spaced and in close proximity to the said rolls, whereby to complete an electromagnetic circuit from said core through said poles and rolls, means for feeding material on to the uppermost of said rolls, means for rotating said rolls, means for diverting and feeding outwardly though said secondary magnet a portion of said material having a shorter trajectory in its discharge from said. uppermost roll, and means for feeding the remainder of said material across the lowermost rolls and for sepits trajectory therebeyond.

5. In a magnetic separator, the combination with a core having vertically spaced laterally member, and means for feeding material across said rolls in series and including means for di- 8. In a magnetic separator, the combination with a receptacle for liquid, of a magnet having 'a Winding above said liquidand poles projecting toward the surface thereof, rolls associated with the respective poles and partially submerged,

arating a portion of said material according to means supporting said rolls upon said frame and a secondary magnet without winding substantialiy wholly submerged in said liquid and comprising a core with an opening in its center and having peripherally spaced poles projecting upwardly to said rolls and the poles of the primary magnet, and discharge conduits extending from the rolls through the opening in its center.'

9. In amagnetic separator, the combination with a receptacle for liquid, of a magnet having a winding above said liquid and poles projecting toward the surface thereof, rolls associated with the respective poles and partially submerged, and a secondary magnet without winding substantially wholly submerged in said liquid and having poles projecting upwardly to said rollsand the poles of the primary magnet, said secondary magnet comprising an open center frame and having a discharge conduit extending from one of the rolls through the openingin its center, together with means directly connecting the pole portions of the primary and secondary magnets for the individual adjustment of said pole portions with' respect to each other, each of said rolls being fixed against displacement with reference to the poles of one of said magnets and adjustable therewith with reference to the corresponding pole of the other magnet.

10. In a magnetic separator, the combination with an electromagnet having upper and lower pole pieces and an intermediate winding, of a secondary magnet comprising a rectangular frame composed of magnetizable material, a support upon which the top and bottom portions of verting a portion of said material through said the secondary magnet are adjustably mounted for movement with reference to the poles of the primary magnet, a set of rolls respectively supported for adjustable movement in correspondence with the movements of the upper and lower portions of the secondary magnet and interposed between its poles and the polesof' the primary magnet, and adjusting screws associated with the support and operatively connected to aomsrs efiect independent adjustments of the upper and wardly directed. apex for flux concentration, a

lower poles and associated rolls of the secondary magnet to independently vary their positions with reference to the poles of the primary magnet.

11. In a magnetic separator, the combination with a receptacle for liquid, of a magnet having a winding above the level of liquid in said receptacle and poles projecting downwardly, rolls connected with the respective poles and com= prising magnetic material rotatable in the fields of the respective poles, each of said rolls being at least partially submerged, and a submerged secondary magnet comprising a substantially horizontal core irame open at its center and free of winding, provided with substantially diametrically spaced poles projecting upwardly into proximity with the respective rolls, feeding devices respectively' arranged to deliver material to said last mentioned poles and beneath said rolls, submerged separating means between said rolls, and separate means for conveying from said receptacle the material separated.

12. In a magneticcseparator, the combination with a receptacle for liquid, of a submerged magnet comprising a core open at its center and provided with upwardly extending poles at opposite sides, each of said poles having an upsecond magnet suspended above the first and provided with downwardly directed poles, magnetic rolls rotatably connected with one of said magnets and disposed between the poles of the upper magnet and the poles of the lower magnet, means disposed within the core of the first mentioned magnet for efiecting-separation of material passing beneath said rolls, and means for delivering 'rnaterial toward the center of said first mentioned magnet across the poles thereof.

13. In a magnetic separator, the combination with a pole and a winding operatively connected for the energization thereof, an opposed pole, a core connected therewith and provided with a central aperture beneath said opposed pole, a roll carried by said core and disposed between said poles, bearing means upon which the roll ROSVWELL H. STEARNS. 

